How I 'Blue Screws'

[tmuir]

I've posted this on another forum but figured it may also be of interest here.

In the future I want to to and make a clock and one of the features of quality clocks is all the screws are 'blued'

I've also got a Bing steam engine to restore that would of originally had Japanned and blued surfaces on it so will be bluing all my replacement screws on it.

Here is a 6BA screw straight out of the packet.

Before it can be blued it needs to be polished so here is an 'Emery Stick' I made to help.

The side showing has 600 W&D on it and the underside has 1200 W&D

Next I needed to make a jig to hold the 6BA screws.
This consisted of a brass rod turned down so the diameter was less than the diameter of the head of the screw. It was then drilled and tapped.

Here is the tapping tool I made a few weeks back being used.

Out of the packet screw in the jig

Screwed after being lightly skimmed

Here the left hand screw has been skimmed and then polished with the 600 and 1200 W&D 'emery stick' whilst in the lathe, the right is one out of the packet.

Getting ready to blue it.
I felt I had to use this hand vice as it was my great grandfathers who was a watchmaker.

To blue I simply hold the bottom of the screw over my meths burner until the top reaches the colour I want.
It first goes yellow and then 'like magic' a lovely blue colour just appears.
Close up before bluing.

Here is is 'Blued'

Job done

 

[itowbig]

cool i like the blue color
thank you for showing us

 

[tmuir]

I know it's pretty basic stuff for most people here but I've got to say one thing I love the most about old pocket watches and clocks is the contrasting blue screws against the brass and I was quiet surprised at just how easy it was to get good results.

I may try polishing the screws with my chamois stick after the W&D next to see if it gives better results.

It also gave me an excuse to 'play' in the workshop for an hour or so.

 

[deverett]

That's basically the way I blue small components, especially tools.

Colour can be controlled by the degree of heating; after blue the piece will go almost black. When the desired colour is reached I dunk the piece in old, very dirty sump oil. The surplus oil is wiped off after it has cooled down. This method seems to give quite good resistance to the dreaded workshop rust bug.

I would advise doing this in fresh air, because the oil gives off quite a dense cloud of smoke and it smells! - to say nothing of the potential fire risk.

Dave
The Emerald Isle

 

[4156df]

tmuir,
I love this "basic stuff" as you call it. Keep it coming. To a lot of us out here this "basic" stuff is "new" stuff.
Dennis

 

[baldrocker]

To a lot of us out here this "basic" stuff is "new" stuff.

4165df
Well said.
BR

 

[SignalFailure]

Nice one tmuir! I've inadvertantly 'blacked' a few items in the past but I like the blue finish. (If you're going to build a clock and use great-grandfather's gear you must make the screws though, not buy them ;D )

 

[Philip]

I frequently blue screws after making them and hardening them, many times I then polish them back to bright since the blueing was to temper them to the spring state. Depends on where it is going to end up.

So, I was curious, what are the condition of screws when purchased? What effect would "blueing" them without rehardening them, have on the steel? I imagine for most purposes it would not make much difference, but I suspect the tradition of blued screws was simply the result of tempering them over the alcohol lamp and since it looked nice against the gilt brass plates of clocks and watches, they saved themselves the step of repolishing.

Philip

 

[tmuir]

Hi,

Personaly I'm not sure what it would do to the hardness but for what they are used for probably woudn't matter much.
I'll leave that question to people that know more than me, hich is a lot or most of the members here. :big:

 

[BobWarfield]

If you are concerned about the hardening, or need to do larger pieces than you want to fool with over heat, there are a variety of cold bluing products available. Look at the firearms gunsmithing catalogs like Brownells. They sell bluing creams that are particularly convenient.

My notes on these and other finishes are here:

http://www.cnccookbook.com/MTMaterialsFinishesTreatmentsHome.htm

Cheers,

BW